I. Field of the Invention
The present invention relates to cyclically repetitive motion generating systems and, in particular, to a mechanism which will generate an output that has a combined epicycloidal and harmonic motion.
II. Description of the Prior Art
Heretofore numerous apparatuses and devices have been utilized to provide a desired motion of an output member along a prescribed path such as the linear indexing mechanism disclosed in U.S. Pat. No. 3,857,292 which is designed to achieve cycloidal motion of an output member along a linear path. Other mechanisms disclosed in the prior art generally achieve cyclically repetitive motion by utilizing complicated cam grooves and followers to accomplish predetermined acceleration, deceleration, dwell, and reversing characteristics of the output member.
To the knowledge of the inventor, such machines and, in particular, the type disclosed in the aforementioned patent have very little flexibility in varying from the cycloidal acceleration curve so as to either increase or decrease the dwell and peak speeds of the output member. Since the dwell periods for such systems have short dwell periods due to the nature of the cycloidal output motion, the electric motor driving such a mechanical mechanism has less revolutions in which to start and stop. Consequently, electrical switches and the like which must be activated by the output member of such mechanisms are activated at a higher speed (i.e. 100 rpm) by a rotating crank member; and, thus, the life expectancy of such switching mechanisms associated with the prior art mechanical devices are considerably shortened.
Because of the size of mechanical devices presently available having cycloidal output motions, the machines must be positioned at the end of a transfer line which, in turn, may be a considerable length, such as 75 to 100 feet long. As such transfer lines are placed into motion, changes in temperature may cause a sufficient change in the length of the transfer bar as to result in the inaccurate positioning of the parts being moved thereon.
In the prior art systems it has also been necessary to utilize a worm gear drive between the prime mover and the cycloidal indexing mechanism; the elimination of such a worm gear drive would result in a more efficient system.
Additionally, the prior art transfer mechanisms of the cycloidal type require that the prime mover (generally an electric motor) be reversed in order to obtain a forward and return movement of the transfer mechanism. It would be desirable to provide a mechanism which does not require the reversal of the electric motor in order to change the direction of movement of the output member.